With development of network technologies, a datacenter has become an infrastructure that provides an Internet service, distributed parallel computing, and the like. Designing an expendable network architecture and an efficient routing algorithm for the datacenter is a research focus in a current academic circle. At the present stage, researchers put forward, based on different rules, a lot of topologies used to construct a datacenter network. A fat-tree topology has been widely applied to the datacenter. A topology rule for constructing a fat-tree network is as follows: In an n-element fat-tree topology, that is, an n-layer fat-tree topology, when n is 3, an entire topology network is divided into three layers that are respectively an edge layer, an aggregation layer, and a core layer from bottom to top. A performance optimization datacenter (Pod) includes switches at the aggregation layer and switches at the edge layer. The entire topology network includes 2n PODs, each POD is connected to n2 hosts (hosts or servers), each POD has n switches at the aggregation layer and n switches at the edge layer, and there are n2 switches at the core layer. Each switch has 2n ports. The network can support (2n)3/4 hosts in total.
Roughly, in the prior art, there are two routing solutions that are based on a fat-tree network. One is convention-based equal-cost multi-path routing (ECMP), that is, there are multiple equal-cost paths between each two switches at the edge layer or each two hosts, and then, packet header information is analyzed, and one of the paths is selected by applying a result of a hash function, so as to implement multi-path load balancing. The other is dynamic routing in which adjusting is performed based on a network traffic. For example, a path is dynamically selected according to a current network status and estimation of a data traffic.
However, neither of the two routing solutions can completely avoid a queuing delay caused by path overlap in a network. Because a link has limited bandwidth and can be used to process only a specific data volume each time, if all data flows pass through a same link, some data flows need to queue. Consequently, a transmission time delay is caused. In the ECMP or the dynamic routing, path overlap is not absolutely avoided in a path selection rule. For example, the ECMP may be approximately considered as randomly selecting a path, and therefore a probability that two selected paths overlap is greater than 0.